The Role of Excessive Water Withdrawals on the Aggravation of the Black Sea
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TITLE: The Role of Excessive Water Withdrawals on the Aggravation of the Black Sea AUTHOR : Michael A . Rozengurt THE NATIONAL COUNCI L FOR SOVIET AND EAST EUROPEA N RESEARC H 1755 Massachusetts Avenue, N .W . Washington, D .C . 20036 PROJECT INFORMATION :* CONTRACTOR : United States Global Strategy Counci l PRINCIPAL INVESTIGATOR : Michael A . Rozengurt COUNCIL CONTRACT NUMBER : 804-2 2 DATE : February 24, 199 3 COPYRIGHT INFORMATIO N Individual researchers retain the copyright on work products derived from research funded b y Council Contract. The Council and the U.S. Government have the right to duplicate written reports and other materials submitted under Council Contract and to distribute such copies within th e Council and U.S. Government for their own use, and to draw upon such reports and materials fo r their own studies; but the Council and U.S. Government do not have the right to distribute, o r make such reports and materials available outside the Council or U .S. Government without th e written consent of the authors, except as may be required under the provisions of the Freedom of Information Act 5 U.S.C. 552, or other applicable law . The work leading to this report was supported by contract funds provided by the National Council fo r Soyiet and East European Research . The analysis and interpretations contained in the report are those of th e author. UNITED STATES GLOBAL STRATEGY COUNCI L WASHINGTON, D.C. The Role of Excessive Water Withdrawal s on the Aggravation of the Black Sea by Michael A. Rozengurt, Ph .D. Senior Research Associate Prepared for The National Council for Soviet and East European Researc h Washington, D.C. EXECUTIVE SUMMARY Prior to the extensive impoundment of rivers of the souther n European slope of the USSR, the oceanographic regime of the Blac k Sea, the world's largest inland water body, was controlled mainl y by excess fresh water influx from the rivers, plus precipitation , over losses due to evaporation . This surplus affected wate r exchanges between the Black and Mediterranean Seas via the Turkis h Strait system . Poor in diversity, but very productive Black Sea biota evolved under to the "harmonious" operation of the majo r large-scale physical, chemical, and biological processes during th e last 7,000 to 10,000 years . At the end of this period, the oxic-anoxic interface reache d its balance, which coincided with the established intrusion o f Mediterranean water . Now, the "natural harmony" of the Black Sea has been disrupted not only in the coastal and estuarine habitats , but in the entire sea . The major reduction of river flow from the northern slope o f the Black Sea began with the development of postwar Soviet wate r management projects . The impoundment of rivers was completed i n the early 1970s . The run-off depletion was further compounded b y development of a massive irrigation network . This, coupled wit h the increased nutrient, organic, and pollutant transports, led t o anoxic events and mass mortalities of marine organisms i n previously productive regions . Acute oxygen deficits also occurre d in the Sea of Azov . In large part, therefore, this paper is a technical report on the hydrology of the Black and Azov Seas . In spite of various conservation programs (industrial wate r recycling, better pollution control, more efficient irrigation , curtailment in hydro energy production, etc .) introduced in th e late 1970s, the loss of fresh water increased so dramatically tha t some remedial measures to arrest the decline in water availabilit y and fisheries in the lower reaches and estuaries have becom e necessary . The ongoing fresh water diversions from the Black Sea and Sea of Azov have a profound effect on the oceanographic regime of th e Marmara-Bosphorus Strait-Black Sea ecosystem . The flow modification affects oceanographic, ecologic, and sanitar y conditions in the Seas . Circulatory patterns are modified on a large scale, including adjacent areas in both Seas . The curren t political and economic havoc, population unrest, and small civi l wars do not give much hope that any attempt to preserve the Blac k Sea will occur in the near future . The new bordering republics ar e nearing military, economic, and political anarchy . Such considerations should cause political leaders to think hard abou t risk assessment of the present situation in the entire Black Se a basin . The most acute potential danger is of a catastrophic releas e and possible explosion of hydrogen sulphide gas (page 46) . TABLE OF CONTENT S ACKNOWLEDGEMENT S ABSTRAC T ii I . INTRODUCTION 1 A . Large-Scale Thermohaline Structure an d Dynamic Mechanisms 2 II . SOME CHEMICAL PHENOMENA AND BIOLGICAL PROPERTIES 1 4 A . Biology 1 5 B . Microflora 1 6 C . Phytoplankton and Zooplankton 2 0 D . Fish Population 2 3 III . THE ROLE OF RUN-OFF REDUCTION ON THE WESTERN BLACK SEA BOSPHORUS STRAIT ECOSYSTEM 3 2 IV . CONCLUSIONS 4 1 V . REFERENCES 4 8 LIST OF FIGURES Figure 1 Major Rivers, Estuarine Regions, and Associated Geographic Settings 4 Figure 2 Turkish Strait System 6 Figure 3 Average Vertical Thermohaline Structure 9 Figure 4 Diagram of Current in the Upper Layer 1 1 Figure 5 Chemical-Microbiological Interactions 1 9 Figure 6 Primary Production by Phytoplankton 2 2 Figure 7 Projects to Regulate Water and Salt Exchange 3 0 Figure 8 Bathymetry 3 5 Figure 9 Schematic Presentation 4 0 Figure 10 Vertical Stratification of Water Masses 45 LIST OF TABLE S Table 1 Major Items of the Black Se a Water Budget (km3 /year ) 1 Table 2 Biomass and Annual Net Productio n of the Main Elements in the Biologica l Structure of the Black Se a 2 5 Table 3 Approximate Reduction of Annua l Riverflow of the Black Sea River s (the Northern Slope) as a Result o f Economic Activities . 2 8 ACKNOWLEDGEMENT S The author is grateful for the support of The National Council for Soviet and Eas t European Research (NCSEER), which provided most of the funding for this study . Th e sponsor, however, is not responsible for the contents or findings of this study . I would like to particularly acknowledge my gratitude to Vladimir I . Toumanoff and Dr. Robert Randolph of the NCSEER. Their understanding of the importance of this study t o political decision makers in the USA has been an inspiration for me . The author is indebted to Ms. Elena London and Dr. David Tolmazin for their unfailing encouragement, moral support, and scientific assistance in researching an d completing this study. I am especially grateful to Dr. Dalton West for his outstandin g editorial help . This study was commenced at the Tiburon Center for Environmental Studies, Sa n Francisco State University and completed at the United States Global Strategy Counci l (Washington . D.C.). I owe a special debt of gratitude for her help in gettin g this study completed to Lynda Cartwright, Director of the Environmental and Energy Study Conferenc e of the Congress of the United States . ABSTRACT This project analyzes the role of the modification of run-off on the ecology of th e Black Sea. Particular attention is given to evaluation of the Black Sea's potential if the current water development policy in this crucial and internationally sensitive area will prevai l in pursuing strictly national, local aims. The project also identifies environmental risks regarding structural transformation o f the Black Sea and illustrates the links between excessive water utilization and the sustainabl e capabilities of marine natural resources. This study may shed considerable light on the cause- and-effect variables in the stagnating of the sea and the impact of these conditions o n biological productivity of the marine environment and public well being . ii I. INTRODUCTION Prior to the extensive impoundment of rivers of the Southern European slope of th e USSR, the oceanographic regime of the Black Sea, the world's largest inland water bod y (Figure 1), was controlled mainly by excess fresh water influx from the rivers, plu s precipitation, over losses due to evaporation (Table 1) . This surplus has affected water exchange between the Black and Mediterranean Seas via the Turkish Strait system (Figure 2) . The only natural obstacle to water flows between the two seas was and is the narrow (0 .76- 3 .60 km width) and shallow (32-34 m deep at its sill) Bosphorus Strait . However, subsequen t water withdrawals for irrigation, municipalities, and industries have be gun to modify th e Black Sea thermohaline structure . As a result, the marine biota has started to experienc e significant negative changes . This study addresses the effect of the current water management (Rozengurt, 1989,1991) and its impact on the physical, chemical, and biologica l properties of the Black Sea; special attention is paid to analysis of the role of the marin e environment's transformation on the future of living conditions of surrounding populace . TABLE 1 - MAJOR 11 EMS OF THE BLACK SEA WATER BUDGET (KM 3/YEAR) Solyankin Solyankin Möller Bruevich (taken fro m Bogdanov a Möller Bruevich (taken from Bogdanova (1928) (1960) Alekin,1966) (1969) (1928) (1960) kin, 1966) (1969) River Run-off 328 350 346* Evaporation 354 350 332 Precipitation 231 225 119 Outflow through 398 400 340 357 the Bosphorus Influx from the 193 175 176 174 Outflow into the –– 32 – Bosphorus Azov Sea Influx from the – – 53 TOTAL 752 750 704 – Azov Sea TOTAL 752 750 694 – Discrepancy 10 – River flows into the Azov Sea are excluded. 1 The descriptions and conclusions are based on the existing historical data set , statistical relationships and specific mechanisms of the water and salt exchange over th e southern and northern sills of the Bosphorus Strait .